Need help with access expression - HELP!!

[MelBSegue]

Status: IIf([PromiseShipDate]>=Date(),"PAST DUE",Format([PromiseShipDate],"mmm yyyy"))

The results are:
Status column shows
Feb 2019
if the PromiseShipDate is 2019-02-28

Want the results to show:
Status column
PAST DUE
if the PromiseShipDate is 2019-02-28

If I change the code to <=Date()
The entire Status column shows PAST DUE